Patent Literature 1 discloses a technique in which a distance from a hindrance to a vehicle is detected and an image captured by an in-vehicle infrared light camera is displayed based on the fact that the detection distance becomes shorter than a reference distance. Patent Literature 1 also discloses a technique in which the reference distance varies in accordance with a vehicle speed, an operation cycle of a windshield wiper, and an operational state of a fog lamp switch.
Among on-board cameras, there is a known on-board camera (hereinafter, referred to as a CCM camera) which is attached to an end portion on one side in a vehicle-width direction and a front end portion, and captures images of the one side in the vehicle-width direction and the front side. As the CCM camera, for example, there is a corner view camera mounted in Lexus (registered trademark) manufactured and sold by Toyota Motor Corporation.
One ideal aim of image displaying is to automatically display an image captured by the on-board camera when a driver desires to see and to automatically prohibit the image from being displayed when the driver desires not to see, thereby realizing image displaying which is useful for the driver without interfering with the driver. The inventor has examined in consideration of the ideal aim thereof that there is room for controlling of the reference distance by a method other than that disclosed in Patent Literature 1.    [Patent Literature 1] JP-2001-71843 A (corresponding to U.S. Pat. No. 6,327,522 B1))